BOTANY 



(Fig. 47, ?•), are also correspondingly long prolongations of single 



epidermal cells. The soft, hairy 

 growths found in young buds 

 are generally similarly prolonged 

 epidermal cells which, as a pro- 

 tective covering, surround the 

 young growing tissues and some- 

 times remain on fully-developed 



Fig.107.— Surfaeeoftheupperepidermisofapetalof plants to shield them from too 



rioia tricolor, showing ridge-iike projections from rapid evaporation and sudden 



the lateral walls, and protruding papillae. (X250.) , 5 , i rrn 



changes of temperature. ihe 

 parts of plants possessing such hairy coverings usually have a white 

 appearance, on account of the air retained both between and in the 



Pig. 108.— Seed-hairs of the cotton, Gossyphm ha- 

 iaceum. A, Part of seed - coat with hairs ( x 3) ; 

 Bx insertion and lower part, B 2 middle part, and 

 -#3 upper part, of a hair. ( x 300.) 



Pig. 109.— Stinging hair of Urtica dioica, 

 with a portion of the epidermis, and, 

 to the right, a small bristle. ( x 60.) 



hairs. The hairs developed from some ot the epidermal cells of the 



